/* jshint curly: false */

/**
* @author       Richard Davey <rich@photonstorm.com>
* @copyright    2016 Photon Storm Ltd.
* @license      {@link https://github.com/photonstorm/phaser/blob/master/license.txt|MIT License}
*/

/**
* A collection of easing methods defining ease-in and ease-out curves.
*
* @class Phaser.Easing
*/
Phaser.Easing = {

    /**
    * Linear easing.
    *
    * @class Phaser.Easing.Linear
    */
    Linear: {

        /**
        * Linear Easing (no variation).
        *
        * @method Phaser.Easing.Linear#None
        * @param {number} k - The value to be tweened.
        * @returns {number} k.
        */
        None: function (k)
        {

            return k;

        }

    },

    /**
    * Quadratic easing.
    *
    * @class Phaser.Easing.Quadratic
    */
    Quadratic: {

        /**
        * Ease-in.
        *
        * @method Phaser.Easing.Quadratic#In
        * @param {number} k - The value to be tweened.
        * @returns {number} k^2.
        */
        In: function (k)
        {

            return k * k;

        },

        /**
        * Ease-out.
        *
        * @method Phaser.Easing.Quadratic#Out
        * @param {number} k - The value to be tweened.
        * @returns {number} k* (2-k).
        */
        Out: function (k)
        {

            return k * (2 - k);

        },

        /**
        * Ease-in/out.
        *
        * @method Phaser.Easing.Quadratic#InOut
        * @param {number} k - The value to be tweened.
        * @returns {number} The tweened value.
        */
        InOut: function (k)
        {

            if ((k *= 2) < 1) { return 0.5 * k * k; }
            return - 0.5 * (--k * (k - 2) - 1);

        }

    },

    /**
    * Cubic easing.
    *
    * @class Phaser.Easing.Cubic
    */
    Cubic: {

        /**
        * Cubic ease-in.
        *
        * @method Phaser.Easing.Cubic#In
        * @param {number} k - The value to be tweened.
        * @returns {number} The tweened value.
        */
        In: function (k)
        {

            return k * k * k;

        },

        /**
        * Cubic ease-out.
        *
        * @method Phaser.Easing.Cubic#Out
        * @param {number} k - The value to be tweened.
        * @returns {number} The tweened value.
        */
        Out: function (k)
        {

            return --k * k * k + 1;

        },

        /**
        * Cubic ease-in/out.
        *
        * @method Phaser.Easing.Cubic#InOut
        * @param {number} k - The value to be tweened.
        * @returns {number} The tweened value.
        */
        InOut: function (k)
        {

            if ((k *= 2) < 1) { return 0.5 * k * k * k; }
            return 0.5 * ((k -= 2) * k * k + 2);

        }

    },

    /**
    * Quartic easing.
    *
    * @class Phaser.Easing.Quartic
    */
    Quartic: {

        /**
        * Quartic ease-in.
        *
        * @method Phaser.Easing.Quartic#In
        * @param {number} k - The value to be tweened.
        * @returns {number} The tweened value.
        */
        In: function (k)
        {

            return k * k * k * k;

        },

        /**
        * Quartic ease-out.
        *
        * @method Phaser.Easing.Quartic#Out
        * @param {number} k - The value to be tweened.
        * @returns {number} The tweened value.
        */
        Out: function (k)
        {

            return 1 - (--k * k * k * k);

        },

        /**
        * Quartic ease-in/out.
        *
        * @method Phaser.Easing.Quartic#InOut
        * @param {number} k - The value to be tweened.
        * @returns {number} The tweened value.
        */
        InOut: function (k)
        {

            if ((k *= 2) < 1) { return 0.5 * k * k * k * k; }
            return - 0.5 * ((k -= 2) * k * k * k - 2);

        }

    },

    /**
    * Quintic easing.
    *
    * @class Phaser.Easing.Quintic
    */
    Quintic: {

        /**
        * Quintic ease-in.
        *
        * @method Phaser.Easing.Quintic#In
        * @param {number} k - The value to be tweened.
        * @returns {number} The tweened value.
        */
        In: function (k)
        {

            return k * k * k * k * k;

        },

        /**
        * Quintic ease-out.
        *
        * @method Phaser.Easing.Quintic#Out
        * @param {number} k - The value to be tweened.
        * @returns {number} The tweened value.
        */
        Out: function (k)
        {

            return --k * k * k * k * k + 1;

        },

        /**
        * Quintic ease-in/out.
        *
        * @method Phaser.Easing.Quintic#InOut
        * @param {number} k - The value to be tweened.
        * @returns {number} The tweened value.
        */
        InOut: function (k)
        {

            if ((k *= 2) < 1) { return 0.5 * k * k * k * k * k; }
            return 0.5 * ((k -= 2) * k * k * k * k + 2);

        }

    },

    /**
    * Sinusoidal easing.
    *
    * @class Phaser.Easing.Sinusoidal
    */
    Sinusoidal: {

        /**
        * Sinusoidal ease-in.
        *
        * @method Phaser.Easing.Sinusoidal#In
        * @param {number} k - The value to be tweened.
        * @returns {number} The tweened value.
        */
        In: function (k)
        {

            if (k === 0) { return 0; }
            if (k === 1) { return 1; }
            return 1 - Math.cos(k * Math.PI / 2);

        },

        /**
        * Sinusoidal ease-out.
        *
        * @method Phaser.Easing.Sinusoidal#Out
        * @param {number} k - The value to be tweened.
        * @returns {number} The tweened value.
        */
        Out: function (k)
        {

            if (k === 0) { return 0; }
            if (k === 1) { return 1; }
            return Math.sin(k * Math.PI / 2);

        },

        /**
        * Sinusoidal ease-in/out.
        *
        * @method Phaser.Easing.Sinusoidal#InOut
        * @param {number} k - The value to be tweened.
        * @returns {number} The tweened value.
        */
        InOut: function (k)
        {

            if (k === 0) { return 0; }
            if (k === 1) { return 1; }
            return 0.5 * (1 - Math.cos(Math.PI * k));

        }

    },

    /**
    * Exponential easing.
    *
    * @class Phaser.Easing.Exponential
    */
    Exponential: {

        /**
        * Exponential ease-in.
        *
        * @method Phaser.Easing.Exponential#In
        * @param {number} k - The value to be tweened.
        * @returns {number} The tweened value.
        */
        In: function (k)
        {

            return k === 0 ? 0 : Math.pow(1024, k - 1);

        },

        /**
        * Exponential ease-out.
        *
        * @method Phaser.Easing.Exponential#Out
        * @param {number} k - The value to be tweened.
        * @returns {number} The tweened value.
        */
        Out: function (k)
        {

            return k === 1 ? 1 : 1 - Math.pow(2, - 10 * k);

        },

        /**
        * Exponential ease-in/out.
        *
        * @method Phaser.Easing.Exponential#InOut
        * @param {number} k - The value to be tweened.
        * @returns {number} The tweened value.
        */
        InOut: function (k)
        {

            if (k === 0) { return 0; }
            if (k === 1) { return 1; }
            if ((k *= 2) < 1) { return 0.5 * Math.pow(1024, k - 1); }
            return 0.5 * (- Math.pow(2, - 10 * (k - 1)) + 2);

        }

    },

    /**
    * Circular easing.
    *
    * @class Phaser.Easing.Circular
    */
    Circular: {

        /**
        * Circular ease-in.
        *
        * @method Phaser.Easing.Circular#In
        * @param {number} k - The value to be tweened.
        * @returns {number} The tweened value.
        */
        In: function (k)
        {

            return 1 - Math.sqrt(1 - k * k);

        },

        /**
        * Circular ease-out.
        *
        * @method Phaser.Easing.Circular#Out
        * @param {number} k - The value to be tweened.
        * @returns {number} The tweened value.
        */
        Out: function (k)
        {

            return Math.sqrt(1 - (--k * k));

        },

        /**
        * Circular ease-in/out.
        *
        * @method Phaser.Easing.Circular#InOut
        * @param {number} k - The value to be tweened.
        * @returns {number} The tweened value.
        */
        InOut: function (k)
        {

            if ((k *= 2) < 1) { return - 0.5 * (Math.sqrt(1 - k * k) - 1); }
            return 0.5 * (Math.sqrt(1 - (k -= 2) * k) + 1);

        }

    },

    /**
    * Elastic easing.
    *
    * @class Phaser.Easing.Elastic
    */
    Elastic: {

        /**
        * Elastic ease-in.
        *
        * @method Phaser.Easing.Elastic#In
        * @param {number} k - The value to be tweened.
        * @returns {number} The tweened value.
        */
        In: function (k)
        {

            var s,
                a = 0.1,
                p = 0.4;
            if (k === 0) { return 0; }
            if (k === 1) { return 1; }
            if (!a || a < 1) { a = 1; s = p / 4; }
            else { s = p * Math.asin(1 / a) / (2 * Math.PI); }
            return - (a * Math.pow(2, 10 * (k -= 1)) * Math.sin((k - s) * (2 * Math.PI) / p));

        },

        /**
        * Elastic ease-out.
        *
        * @method Phaser.Easing.Elastic#Out
        * @param {number} k - The value to be tweened.
        * @returns {number} The tweened value.
        */
        Out: function (k)
        {

            var s,
                a = 0.1,
                p = 0.4;
            if (k === 0) { return 0; }
            if (k === 1) { return 1; }
            if (!a || a < 1) { a = 1; s = p / 4; }
            else { s = p * Math.asin(1 / a) / (2 * Math.PI); }
            return (a * Math.pow(2, - 10 * k) * Math.sin((k - s) * (2 * Math.PI) / p) + 1);

        },

        /**
        * Elastic ease-in/out.
        *
        * @method Phaser.Easing.Elastic#InOut
        * @param {number} k - The value to be tweened.
        * @returns {number} The tweened value.
        */
        InOut: function (k)
        {

            var s,
                a = 0.1,
                p = 0.4;
            if (k === 0) { return 0; }
            if (k === 1) { return 1; }
            if (!a || a < 1) { a = 1; s = p / 4; }
            else { s = p * Math.asin(1 / a) / (2 * Math.PI); }
            if ((k *= 2) < 1) { return - 0.5 * (a * Math.pow(2, 10 * (k -= 1)) * Math.sin((k - s) * (2 * Math.PI) / p)); }
            return a * Math.pow(2, -10 * (k -= 1)) * Math.sin((k - s) * (2 * Math.PI) / p) * 0.5 + 1;

        }

    },

    /**
    * Back easing.
    *
    * @class Phaser.Easing.Back
    */
    Back: {

        /**
        * Back ease-in.
        *
        * @method Phaser.Easing.Back#In
        * @param {number} k - The value to be tweened.
        * @returns {number} The tweened value.
        */
        In: function (k)
        {

            var s = 1.70158;
            return k * k * ((s + 1) * k - s);

        },

        /**
        * Back ease-out.
        *
        * @method Phaser.Easing.Back#Out
        * @param {number} k - The value to be tweened.
        * @returns {number} The tweened value.
        */
        Out: function (k)
        {

            var s = 1.70158;
            return --k * k * ((s + 1) * k + s) + 1;

        },

        /**
        * Back ease-in/out.
        *
        * @method Phaser.Easing.Back#InOut
        * @param {number} k - The value to be tweened.
        * @returns {number} The tweened value.
        */
        InOut: function (k)
        {

            var s = 1.70158 * 1.525;
            if ((k *= 2) < 1) { return 0.5 * (k * k * ((s + 1) * k - s)); }
            return 0.5 * ((k -= 2) * k * ((s + 1) * k + s) + 2);

        }

    },

    /**
    * Bounce easing.
    *
    * @class Phaser.Easing.Bounce
    */
    Bounce: {

        /**
        * Bounce ease-in.
        *
        * @method Phaser.Easing.Bounce#In
        * @param {number} k - The value to be tweened.
        * @returns {number} The tweened value.
        */
        In: function (k)
        {

            return 1 - Phaser.Easing.Bounce.Out(1 - k);

        },

        /**
        * Bounce ease-out.
        *
        * @method Phaser.Easing.Bounce#Out
        * @param {number} k - The value to be tweened.
        * @returns {number} The tweened value.
        */
        Out: function (k)
        {

            if (k < (1 / 2.75))
            {

                return 7.5625 * k * k;

            }
            else if (k < (2 / 2.75))
            {

                return 7.5625 * (k -= (1.5 / 2.75)) * k + 0.75;

            }
            else if (k < (2.5 / 2.75))
            {

                return 7.5625 * (k -= (2.25 / 2.75)) * k + 0.9375;

            }
            else
            {

                return 7.5625 * (k -= (2.625 / 2.75)) * k + 0.984375;

            }

        },

        /**
        * Bounce ease-in/out.
        *
        * @method Phaser.Easing.Bounce#InOut
        * @param {number} k - The value to be tweened.
        * @returns {number} The tweened value.
        */
        InOut: function (k)
        {

            if (k < 0.5) { return Phaser.Easing.Bounce.In(k * 2) * 0.5; }
            return Phaser.Easing.Bounce.Out(k * 2 - 1) * 0.5 + 0.5;

        }

    }

};

Phaser.Easing.Default = Phaser.Easing.Linear.None;
Phaser.Easing.Power0 = Phaser.Easing.Linear.None;
Phaser.Easing.Power1 = Phaser.Easing.Quadratic.Out;
Phaser.Easing.Power2 = Phaser.Easing.Cubic.Out;
Phaser.Easing.Power3 = Phaser.Easing.Quartic.Out;
Phaser.Easing.Power4 = Phaser.Easing.Quintic.Out;
